Clamping devices for fixing line wires to insulator blocks



'Nov. 19, 1957 DUKLAET 2,813,923

CLAMPING DEVICES FOR FIXING LINE WIRES TO INSULATOR BLOCKS Filed Sept. 24. 1953 IN VEN-TOR Hard/a Oak/c226 Ii TTORIYE i United States Patent CLAMPING DEVICES FOR WIRES TO INSULATOR BLOGKS Harald Duklaet, Steinkjer, Norway, assignor' to Trygve Greiif, Oslo, Norway Application September 24, 1953, Serial No. 382,144 4 Claims. (Cl. 174-169) The present invention relates to clamping devices for fixing line wires to insulator blocks, which devices each comprise a clamp for carrying the line wire which may be called a line wire clamp and a clamp for attachment to the top of the insulator block which may be called the insulator clamp.

It is an object of the present invention to provide a clamping device of the aforesaid kind in which the line wire clamp is connected with the insulator clamp by means which enable the line wire clamp to oscillate in a vertical and a horizontal plane relative to the insulator clamp.

A clamping device which enables the line Wire clamp to oscillate both in the vertical and in the horizontal plane has been found particularly useful in connection with overhead transmission lines in difiicult, that is to say, in undulating terrain as well as in mountainous terrain subject to strong hoarfrost formation.

According to the present invention a clamping device for fixing a line wire to an insulator block consists of a line Wire clamp for supporting the line wire and an insulator clamp for attachment to an insulator block, wherein the line wire clamp has substantially midway between its extremities, a spherical enlargement and the insulator clamp is provided with a seat in which the enlargement may be secured so that the line wire clamp is able to rotate about a longitudinal axis and has limited freedom of oscillation both in the horizontal and the vertical plane.

By Way of example an embodiment of the invention will now be described with reference to the accompanying drawing in which:

Fig. 1 is a side elevation of a clamping device,

Fig. 2 is a plan view of the clamping device with one part out off, and

Fig. 3 is a section on III-III in Fig. 1.

In the drawing there is represented the top portion of an insulator block in the upper face of which is formed a groove 2 which receives the cross bolt 3 of the insulator clamp, the cross bolt 3 joins together the two arcuate clamping members 4 and 5 which grip round a neck in the insulator block. The line wire clamp consists in a channel 22 of U-shaped cross section the base of which is substantially semi-circular. The line wire is fastened in the channel 22 by means of one or more shackle bolts 23 each of which carries nuts 24 and a butt strap 25 by means of which a clamping shoe 26 may be pressed against the line wire. At or near its middle the channel 22 has a spherical enlargement 27 whose centre is at some distance above the center of curvature of the semi-circular base of the channel 22 (Fig. 3). The enlargement 27 has a slot 27' extending upwards from the base of the channel 22 and having a width substantially equal to the Width of the mouth of the channel.

The spherical enlargement 27 rests in a U-shaped bearing member 28 which is welded to the cross bolt 3 of the insulator clamp. In a normal cross section through the vertical arms of the bearing member 28 the arms ap- 2,813,923 Patented Nov. 19, 1957 the top ends of the arms of the member 28, and said bolt holds in position alid-lik'e member 30.

This'member 30 maintains a minimum separation between the two arms a'ndat the same time acts as a stop limitingthe upwardmoveen'tof the line: wire clamp.

The line wire clamp borne in this fashion is able to rotate and at the same time to perform a limited oscillatory movement but without being able to move longitudinally in its bearing. Moreover, owing to the fact that the centre of curvature of the base of the channel 22 is lower than the centre of the spherical enlargement 27, the load pressure of the line wire clamp will always attack below said centre The channel 22 is curved in its longitudinal direction; if desired, the curvature may increase towards the ends of the channel, as has been indicated by a broken line in Fig. 1. Furthermore, the width of the opening of the channel may increase towards its ends, as shown in Fig. 2, to allow the line wire a certain freedom of lateral movement.

In the embodiment described above it has been assumed that the spherical enlargement 27 is formed integrally with the channel, but it will be readily understood that, alternatively, the enlargement may be made independently of the channel and suitably attached to the latter.

Apart from the fact that the distance from the top of the insulator block to the line wire will be very small in the illustrated clamping device, the new design is particularly favourable from the standpoint of convenience for installation.

When the line wire is to be suspended, it is first played out in the conventional manner by means of mounting jigs and tensioned in these jigs to the desired sag, whereupon the clamping points are marked, for example with a piece of insulating tape. The line wire is then taken off the jigs and the line Wire clamps are attached in the correct positions. The final work involved in the suspension of the line wire thus merely consists in inserting the individual line wire clamps into their respective bearing members 28, and placing the lid-like members 30 and the bolts 29 in position.

The invention is not restricted to the details of the embodiment shown in the drawing and described above. Thus, for example, the insulator clamp may be replaced by a metal cap placed on the head of the insulator block and cemented on to it. Such an arrangement has the advantage that it is less liable to cause radio interference.

I claim:

1. A clamping device for fixing a line wire to an insulator block, said device comprising a clamp structure by which the device is mounted upon the insulator block, said clamp structure including a bearing block having a hollow semi-cylindrical seat, a line wire clamp having a longitudinal groove for receiving the line wire and a central spherical portion for engagement with said semi-cylindrical seat to mount the line wire clamp upon said clamp structure, said spherical portion having a slot which registers with said groove and said bearing block having elongated guide structure guiding said spherical portion for translational motion with respect to said bearing block.

2. The invention as defined in claim 1, the center of said slot being vertically spaced from the center of said groove, whereby the line wire forces are exerted upon said clamp below the center of said spherical portion.

3. The invention as defined in claim 1, said guide structure having spaced apart arms and said arms having interior guide surfaces-curved to conform with the surface I i of said spherical portion, said spherical portion having e 7 bearing contact with said interior guide surfaces.

4. The invention as claimed in clairn 1, said guide structure Being of channel form,'1the interior surfaces of the channelfsides beingcurv'edto correspond with the surface of said spherical portion, said spherical portion having bearing contact with said interior surfaces and being guided by said surfaces for translational motion References Cited in the file of this patent UNITED STATES PATENTS Goddard July 22, 1919 Gehrig Aug. 14, 1923 Frey et a1. July 5, 1949 FOREIGN PATENTS Germany Mar. 19, 1926 Germany 'Dec. 30, 1926 Switzerland Feb. 1, 1937 

